When transporting cargo in a shipping container, loading and unloading of the cargo into and out of the shipping container is carried out, as shown in JP 11-60187 A for example, through the opening formed by opening doors at the rear end of the shipping container (see FIG. 1 of JP 11-60187 A). In this case, a transport vehicle such as a forklift is used for the loading and unloading of the cargo. However, when transporting long objects such as lumber or steel materials, as cargo, there is a problem that a bundle of a plurality of such long objects may break during the loading and unloading thereof, and the end portions of the scattered long objects may come into contact with the inner surfaces of the shipping container, to cause damage to the inner surfaces or to the long objects themselves. In addition, loading and unloading of a large number of long objects into and out of the shipping container through the doors is a complicated operation, which consumes time and cost.
In view of this, it has been proposed to install a cargo bed for long objects to a transportation vehicle, as shown in JP 2015-696 A, for carrying out the transportation of long objects. This cargo bed includes a plurality of fall prevention columns vertically extending from both the right and left sides of its floor surface, at positions bilaterally symmetrical to each other (See e.g., FIG. 1 of JP 2015-696 A). The fall prevention columns serve to prevent the falling of the long objects loaded on the floor surface from the right and left sides of the floor surface. Since no top plate is provided on top of the fall prevention columns, the loading of the long objects can be carried out directly from above the cargo bed (see FIG. 6 in JP 2015-696 A).
However, the cargo bed for long objects disclosed in JP 2015-696 A is for use in a transportation vehicle such as a truck, and thus, in order to load long objects loaded on the cargo bed for long objects, into a container ship, it is necessary to unload the long objects from the cargo bed and to reload them into a shipping container. This reloading operation is extremely complicated, and causes an increase in the cost as a result thereof. In addition, there is a potential risk for other problems such as the occurrence of damage in the long objects during the reloading.